Generally, a hydraulic excavator as a construction machine is largely constituted by an automotive lower traveling structure, an upper revolving structure which is swingably mounted on the lower traveling structure, and a working mechanism liftably mounted on the front side of the upper revolving structure.
The upper revolving structure is largely constituted by a revolving frame serving as a support structure, an engine which is mounted on the rear side of the revolving frame and drives a hydraulic pump, a cooling fan which is rotatively driven by the engine, heat exchanger such as a radiator and an oil cooler which are provided in face-to-face relation to the cooling fan, and an exterior cover provided over the revolving frame to cover the mounted equipment such as the engine, the cooling fan, and the heat exchanger.
Here, the exterior cover is constituted by a top plate provided in such a manner as to extend horizontally over upper sides of the respective mounted equipment and left and right side plates respectively extending downward from both left and right ends of the top plate toward the revolving frame. A large opening for the inspection and maintenance of the engine, the heat exchanger, and the like is provided in the top plate.
Accordingly, an openable engine cover is attached to the top plate to close the aforementioned opening, and the engine cover is formed widely in the left-right direction so as to cover from the heat exchanger to the hydraulic pump. An inlet port is provided on the left side of the engine cover to suck cooling air from the outside toward the heat exchanger when the cooling fan is rotatively driven, while an exhaust port is provided on the right side thereof to exhaust to the outside the cooling air which has passed through the heat exchanger and the cooling fan (Patent Literature 1: Japanese Patent Laid-Open No. 2000-303497 A, and Patent Literature 2: Japanese Utility Model Laid-Open No. H7-30321).
Incidentally, with the hydraulic excavators according to the above-described patent literatures, the configuration provided is such that the engine cover is openably provided on the top plate of the exterior cover, and the inlet port and the exhaust port are provided in this engine cover.
Here, in performing such as the inspection operation and maintenance operation of the engine and the like, the engine cover is opened, and an operator gets on the top plate to perform the operation. However, in the case where the configuration provided is such that a large opening is provided in the top plate and this opening is covered by the engine cover, with a small-size hydraulic excavator in which the upper revolving structure is formed compactly, there is a problem in that it is impossible to secure a space for the operator to get on the top plate, so that the workability in the maintenance operation is aggravated.
Accordingly, with a small-size hydraulic excavator, it has been conceived to provide a small opening only on the upper side of the heat exchange device requiring periodic inspection operation, cleaning operation, and the like and to openably mount a heat exchanger cover to the top plate so as to cover only the heat exchange device. In this case, it is possible to secure a space for the operator to get on the top plate in the operation.
However, in the case of the configuration in which the upper side of the heat exchange device is covered by the small heat exchanger cover, the inlet port and the exhaust port provided in this heat exchanger cover would be located close to each other. For this reason, there is a problem in that a recirculation can occur in which warmed air discharged from the exhaust port is sucked again from the inlet port, causing deterioration in the cooling efficiency of fluids by the heat exchanger.